Propeller



Oct. 4, 1938. I c. l -l. HAVILL 2,132,162

I PROPELLER Filed May 16, 1936 2 Sheets-Sheet 1 Imn V ir v mum/Ma a C. H. HAVILL Oct. 4, 1938.

PROPELLER Filed May 16, 1936 2 SheetsSheet 2 gwue/wtoo CZmZ'OR /I. Hal/1 Patented Oct. 4, 1938 UNITED STATES PATENT OFFICE 2,132,162 PROPELLER Application May 16, 1936, Serial No. 80,212

10 Claims.

This invention relates to propellers and more particularly to propellers of the type having blades, the pitch of which may be automatically varied during operation.

One of the objects of the present invention is to provide, in a variable pitch propeller of the automatic type, a novel construction for effectively limiting the reduction in blade pitch to the end that the rate of revolutions of the engine driving the propeller may be maintained within predetermined limits.

Another object is to adapt a novel pitch-limiting construction to a propeller of the type having a hub, slidable along the propeller shaft for changing the pitch of the blades.

Still another object is to utilize, in a novel manner, the effects of centrifugal force upon a member displaced from the propeller shaft axis in order to determine the amount of reduction in blade pitch in accordance with engine speed.

A further object is to provide a propeller having a plurality of blades, the pitch of which is automatically varied during operation in accordance with the thrust of the blades in combination with a novel structure including a centrifugally-responsive link mechanism for effectively limiting the pitch which the blades may attain.

A still further object is to associate a novel pitch-limiting arrangement with the pitchchanging linkage of a propeller of the type embodying a hub movable axially of the driving shaft for changing the pitch of the blades in accordance with the thrust of the latter.

Other objects and novel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawings.- It is to be expressly understood, however, that the drawings are employed for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings, wherein similar reference characters refer to similar parts through the several views: I

Fig. 1 is an axial view, partly in section, of a propeller embodying the principles of the present invention, and

Fig. 2 is an axial view, partly in section, of the parts shown in Fig. 1 and taken along a plane perpendicular to that of Fig. 1.

Referring more particularly to Fig. 1, a vari- -tion I! of the driving block I by a pin I3.

able pitch propeller embodying the principles of the present invention is illustrated therein as being constituted by a rotatable engine shaft or extension thereof 3, and a hub 4 drivably connected thereto but relatively movable longitudinally thereof in response to the thrust exerted by the blades, the hub being provided with a plurality of radially-extending sockets 5 adapted to rotatably receive the inner or root ends of propeller blades 6, there being also provided suitable means for rotating the blades 6 in their respective sockets to vary the pitch of said blades during the aforesaid thrust-responsive movement of the hub relative to the shaft, as will appear more fully hereinafter.

l5 For effecting a drivable connection between the hub 4 and the shaft 3', a driving member or block 1 is suitably splined to the shaft as by means of splines 8, and is preferably rigidly maintained thereon by any suitable means, such as, for ex- 20 ample, split front and rear cones 9' and NJ respectively, a nut H threadedly received by the outer end of the shaft 3 and interlocked with the front cone 9 being provided for maintaining these parts in proper operative relation with respect to the shaft. After assembly of the elements heretofore mentioned, the nut H is preferably locked to an outwardly-extending por- The hub is provided with a centrally-disposed open- 30 ing for receiving the driving block, and suitable anti-friction bearings, not shown, are provided between the hub and said block in order that relative movement between these parts may take place in a substantially frictionless manner.

In order to effect pitch-changing movement of the blades during the aforesaid thrust-responsive movement of the hub with respect to the drive shaft, each blade is connected with the shaft by means of a link mechanism. Referring more particularly to Fig. 2, such mechanism includes a link I4 pivotally connected at one end to a bolt l5 carried by a plate It, the latter being preferably formed integrally with the driving block I and hence thereby rigidly se- 4 will be rotated by such mechanisms in order to change the pitch during relative movement between the hub and propeller shaft in response to changes in thrust of the blades.

In order to yieldingly oppose forward axial movement of the hub with respect to the shaft for the purpose of arresting such movement at certain positions along the shaft in accordance with the degree of thrust exerted by the blades under the existing conditions, there is provided a plurality of resilient members, such as, for example, coil springs I8, arranged in a circle concentric with respect to the shaft and interposed between the hub 4- and a plate l9 secured in any, suitable manner to the portion I2 of the driving block 1. It is here pointed out that when the parts are in the position shown in Fig. 1, the pitch of the blades is a maximum, the same being gradually reduced, however, during forward movement of the hub relative to the shaft. The above mentioned springs l8 serve to yieldably oppose such movement and to arrest the hub when a balance is obtained between the spring forces and the forward thrust of the propeller. It will be understood that the movement of the hub will thus be arrested at various points along the propeller shaft dependent upon the propeller blade thrust and that the pitch of the blades will therefore be substantially proportional to the thrust thereof.

One of the features of the present invention resides in the provision of means for limiting the reduction in the pitch of the blades to the end that an increase in engine speed beyond a predetermined value will be avoided. As shown, such means is subjected to centrifugal force during operation of the propeller and comprises a pair of pivotally-connected links 20 and 2| respectively connected to the hub as by means of a bracket 22 and to the stud IT as by means of screw 23. A linkage of this character is provided for each of the blades, and as will be observed in Fig. 2, the links are normally angularly related to each otherby an angle approaching a right angle. During operation of the propeller, it will be appreciated that centrifugal force acting at the pivot 24 of said links has a tendency to move the hub downwardly, as viewed in Fig.

2, to increase the pitch of the blades. However during operation at normal engine speed, this eifect will be insufficient to act as a limit for the reduction in pitch of the blades. However, as the thrust of the blades increases, it will be observed that the angularity between links 20 and 2| increases and approaches a straight line.- Furthermore, centrifugal force acting upon the pivot 24' will exert a greater limiting effect upon the forward movement of the hub due to the toggle action of the links 20 and 2| upon the hub and stud I1 respectively. At a predetermined relatively high engine speed, the centrifugal force upon the pivot 24 will be such as to prevent further movement of the hub with respect to the shaft in a direction to effect a further decrease in the pitch of the blades. Thus, due to the toggle action of links 20 and 2|, the lower pitch 7 limit of the blades may be predetermined and the propeller acts as a governor to prevent an increase in engine speed beyond the value preselected.

While there has been shown and described only one embodiment of the invention, it is to be understood that the same is not limited thereto but may be embodied in various forms. It is also to be understood that changes may be made in relative sizes, shapes and relative locations of the component parts of the invention and that certain parts may be utilized without others, if desired, without departing from the spirit of the invention, as well understood by those skilled in the art. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. In apropeller having a hub,'a plurality of blades carried thereby, a rotatable shaft drivably connected with the hub, said hub being automatically movable axially of said shaft for varying the pitch of the blades, means interconnecting said shaft and blades for varying the pitch of the latter during such axial movement of the hub, and means including a pair of links connecting said hub and interconnecting means for limiting said axial movement of the hub.

2. In a propeller having a hub, a plurality of blades carried thereby, a rotatable shaft drivably connected with the hub, said hub being automatically movable axially of said shaft for varying the pitch of the blades, means interconnecting said shaft and blades for varying the pitch of the latter during such axial movement of the hub, and means for limiting the axial movement of the hub in one direction including a pair of pivotally-connected members connecting said hub and interconnecting means.

3. An aircraft propeller comprising a rotatable shaft, a hub surrounding said shaft and drivably connected thereto, a plurality of blades rotatably mounted with respect to the hub, thrust-responsive means for moving said hub rectilinearly on said shaft and including a link mechanism comprising a pair of pivotally-connected links for automatically rotating said blades with respect to the hub for varying the angularity of said blades during such movement of the hub, and means responsive to centrifugal force for limitingthe rectilinear movement of the hub on the shaft comprising members interconnecting one of said links and hub. v

4. An aircraft propeller comprising a rotatable shaft, a hub surrounding said shaft and drivably connected thereto, a plurality of blades rotatably mounted with respect to the hub, thrustresponsive means for moving said hub rectilinearly on said shaft and including a link mechanism for automatically rotating said blades with respect to the hub for varying the 'angularity of said blades during such movement of the hub, and means for limiting the rectilinear movement of the hub including a toggle mechanism having parts interconnected between the movable hub and link mechanism and being responsive to centrifugal force.

5. In a variable pitch propeller having a shaft, a plurality of blades, a hub rotatably mounting said blades and slidable along said shaft in response to the thrust of the blades, means interconnecting said blades and shaft for varying the pitch of the former during thrust-responsive movement of the hub, and means including a pair of pivotallyconnected links connecting said interconnecting means and hub and responsive to centrifugal force for limiting the thrust-responsive movement of the hub after a predetermined speed of rotation has been attained.

6. In a variable pitch propeller having a shaft,

a plurality of blades, a hub rotatably mounting I the pitch of the former during thrust-responsive movement of the hub, resilient means for yieldingly opposing said movement of the hub, and centrifugally-responsive mechanism for limiting the decrease in the pitch of the blades including relatively-movable pivotally connected members interconnected between said first named means and hub.

'7. In a propeller having a hub, a plurality of blades carried thereby, a rotatable shaft drivably connected with the hub, said hub being automatically movable axially of said shaft for varying the pitch of the blades, means interconnectingsaid shaft and blades for varying the pitch of the latter during such axial movement of the hub, and means for limiting said axial movement of the hub comprising a centrifugally-responsive toggle mechanism having parts interconnecting said movable hub and interconnecting means.

8. In a propeller having a hub, a plurality of blades carried thereby, a rotatable shaft drivably connected to the hub, said hub being automatically movable axially of the shaft for varying the pitch of the blades, and means interconnecting said shaft and blades for varying the pitch of the latter during such axial movement of the hub, said means comprising a member secured to each blade and projecting through the hub, a member secured to the shaft and extending laterally on opposite. sides thereof, said last named member being positioned exteriorly of the hub, links pivotally connecting said last named member and said blade members, and means connecting said hub and links for automatically limiting the extent of axial movement of the hub in one direction.

9. In a propeller having a hub, a plurality of blades carried thereby, a rotatable shaft drivably connected to the hub, said hub being automatically movable axially of the shaft for varying the pitch of the blades, and means interconnecting said shaft and blades for varying the pitch of the latter during such axial movement of the hub, said means comprising a member secured to each blade and projecting through the hub, a member secured to the shaft and extending laterally on opposite sides thereof, said last named member being positioned exteriorly of the hub, means connecting said last named member and said blade members, and a toggle mechanism having a part connected with said hub and a part connected with said first member and'responsive to centrifugal force for limiting said axial movement of the hub.

10. In a propeller having a plurality of blades, a shaft, a hub mounting said blades and slidable along said shaft in response to the thrust of the blades, means connecting said blades and shaft and effective to change the blade pitch during such movement of the hub along the shaft, and other means including relatively movable elements pivotally connecting the hub and first means and responsive to centrifugal force for checking said movement of the hub.

CLINTON H. HAVILL. 

